Iron(II) and Nickel(II) Complexes of 2,6-Di(thiazol-2-yl)pyridine and Related Ligands

1991 ◽  
Vol 44 (8) ◽  
pp. 1041 ◽  
Author(s):  
AT Baker ◽  
P Singh ◽  
V Vignevich
Keyword(s):  
High Spin ◽  
Room Temperature ◽  
Spin Transition ◽  
Magnetic Behaviour ◽  
Diethyl Acetal ◽  
Thermally Induced ◽  
Field Strengths

2,6-Di(thiazol-2-yl]pyridine (1a), 2,6-di(4-methylthiazol-2-yl)pyridine (1b) and 2,6-di(2-imid-azolin-2-yl)pyridine (3) have been prepared by the reaction of pyridine-2,6-dicarbothioamide with bromoacetaldehyde diethyl acetal, bromoacetone and ethylenediamine, severally. Bis ( ligand ) iron(II) and nickel(II) complexes of all ligands have been prepared. The bis ( ligand ) iron(II) complexes of (1a) and (3) are low-spin whereas that of (1b) is high-spin at room temperature and undergoes a thermally induced spin transition. The field strengths of the ligands , determined from the spectra of their nickel(II) complexes, correlate well with the observed magnetic behaviour of their iron(II) complexes. The field strengths of (1a) and (1b) are found to be marginally less than those of the isomeric ligands 2,6-di(thiazol-4-yl)pyridine (2a) and 2,6-di(2-methylthiazol-4-yl)pyridine (2b).

Optical Microscopy Imaging of the Thermally-Induced Spin Transition and Isothermal Multi-stepped Relaxation in a Low-Spin Stabilized Spin-Crossover Material

2021 ◽  
Author(s):  
Pradip Chakraborty ◽  
Mouhamadou Sy ◽  
Houcem Fourati ◽  
Maria Teresa Delgado Pérez ◽  
Mousumi Dutta ◽  
...  
Keyword(s):  
Optical Microscopy ◽  
High Spin ◽  
Spin Relaxation ◽  
Spin Crossover ◽  
Spin Transition ◽  
Host Lattice ◽  
Microscopy Imaging ◽  
Thermally Induced ◽  
Optical Microscopy Imaging

The thermal spin transition and the photo-induced high-spin → low-spin relaxation of the prototypical [Fe(ptz)6](BF4)2 spin-crossover compound (ptz = 1-propyltetrazole) diluted in the isostructural ruthenium host lattice [Ru(ptz)6](BF4)2, which stabilizes...

Structural Changes in Iron(II) Polymeric Complexes upon Thermally and Optically Induced Spin Transition Determined by EXAFS Spectroscopy

1998 ◽  
Vol 524 ◽  
Author(s):  
S. B. Erenburg ◽  
N. V. Bausk ◽  
L. G. Lavrenova ◽  
Yu. G. Shvedenkov ◽  
L. N. Mazalov
Keyword(s):  
High Spin ◽  
Structural Changes ◽  
Mutual Influence ◽  
Chemical Shifts ◽  
Spin Transition ◽  
High Spin State ◽  
Local Environment ◽  
Thermally Induced ◽  
Polymeric Complexes ◽  
Electronic And Spatial Structure

ABSTRACTChanges in the electronic and spatial structure of polymeric Fe(II) complexes with 1,2,4- triazoles and various anions upon spin transition was studied using EXAFS and XANES spectroscopy. Spin transition and structural changes were induced by variations of the anion, dilution with Zn, under heating or the action of light. In all complexes, the spin transition is accompanied by drastic changes in the local environment of Fe atoms. The increase in spin transition temperature for the complexes with variable anions CIO4-, I-, Br-, BF4-, NO3- was found to correlate with changes in the Fe-N distances and changes in bond covalence determined from the chemical shifts in Mössbauer spectra. High spin metastable long life states were detected and studied in the polymeric complex Fe(atrz)3(ClO4)2. It was established that the changes in structure of polymeric complexes upon the transition to a metastable high spin state under the action of light differ from those in the thermally induced spin transition. Such differences are determined by mutual influence of Fe atoms in high spin and low spin states in polymeric chains.

Demonstration of the thermally induced high spin–low spin transition for a transparent spin crossover complex film [Fe(II)(H-trz)3]-Nafion (trz=triazole)

Polyhedron ◽  
2005 ◽  
Vol 24 (16-17) ◽  
pp. 2909-2912 ◽  
Author(s):  
Akio Nakamoto ◽  
Norimichi Kojima ◽  
Liu XiaoJun ◽  
Yutaka Moritomo ◽  
Arao Nakamura
Keyword(s):  
High Spin ◽  
Spin Crossover ◽  
Spin Transition ◽  
Thermally Induced ◽  
Complex Film

Metal-Complexes of 1,10-Phenanthroline Derivatives. XV. Complexes of 2-(3,5-Dimethylpyrazol-1-yl)-1,10-phenanthroline

1988 ◽  
Vol 41 (6) ◽  
pp. 873 ◽  
Author(s):  
AS Abushamleh ◽  
HA Goodwin
Keyword(s):  
Magnetic Properties ◽  
Solid State ◽  
Spectral Data ◽  
High Spin ◽  
Nickel Complex ◽  
Spin Transition ◽  
Critical Value ◽  
Magnetic Data ◽  
Strong Temperature Dependence ◽  
Thermally Induced

Iron(II) and nickel(II) bis ( ligand ) complexes of 2-(3,5-dimethylpyrazol-1-yl)-1,10-phenanthroline (L) have been prepared. The field strength of L as determined from spectral data for the nickel complex is in the range encompassing the critical value at the singlet (1A1) ↔ quintet (5T2) crossover for iron(II). The magnetic properties of the iron(II) complex both in solution and in the solid state are anomalous, and indicative of the occurrence of a thermally induced spin transition. Mossbauer spectral data confirm this, and reveal separate contributions from the singlet and quintet species with a strong temperature-dependence of their relative intensities. Magnetic data for the complex in solution are consistent with a simple high spin ↔ low spin equilibrium, and lead to values of ΔH = 23�0.5 kJ mol-1 and ΔS = 66�5 J K-1 mol-1 for the low spin → high spin transformation.

Realizing bias-induced spin transition with high-spin MnII complexes at room temperature

2017 ◽  
Vol 5 (44) ◽  
pp. 11598-11604
Author(s):  
Hua Hao ◽  
Ting Jia ◽  
Xiaohong Zheng ◽  
Lingling Song ◽  
Zhi Zeng
Keyword(s):  
High Spin ◽  
Spin State ◽  
Ground State ◽  
Room Temperature ◽  
State Transition ◽  
Spin Transition ◽  
Memory Devices ◽  
Spin State Transition ◽  
Molecular Transistors ◽  
Magnetic Ions

Complexes in the ground state with high-spin magnetic ions (3d5/3d4) can be used to realize the electrically-induced spin-state transition and build room-temperature molecular transistors or memory devices.

Thermally Induced High-Spin Low-Spin Transition in Co[Cr0.5Ga1.5]S4 Spinel

2011 ◽  
Vol 170 ◽  
pp. 9-12
Author(s):  
J. Krok-Kowalski ◽  
Ewa Maciążek ◽  
Tadeusz Groń ◽  
Andrzej W. Pacyna ◽  
Tadeusz Mydlarz ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
High Spin ◽  
Inflection Point ◽  
Spin Transition ◽  
Spin Frustration ◽  
Strong Suppression ◽  
Thermally Induced ◽  
Tetrahedral Sites ◽  
Curie Temperature Tc

A high spin (HS) – low spin (LS) transition has been discovered in the Co[Cr0.5Ga1.5]S4 spinel, where the Co ions occupy tetrahedral sites and the Cr and Ga ions octahedral ones. The latter are diluted by the non-magnetic Ga-ions. Application of magnetic fields revealed ferrimagnetic order with a Curie temperature TC = 126 K, a strong suppression of the magnetic susceptibility () and a slight shift of TC to lower temperatures. A cusp at 15.6 K on the ac (T) curve suggests a spin frustration of the re-entrant type. Characteristic for the HS-LS transition is an inflection point at 150 K on the 1/(T) curve, a lack of the Curie-Weiss region above TC and a small value of the magnetization, 4.76 emu/g at 4.4 K and at a magnetic field of 57.5 kOe.

An iron(II) complex tripodally chelated with 1,1,1-tris(pyridin-2-yl)ethane showing room-temperature spin-crossover behaviour

2016 ◽  
Vol 72 (11) ◽  
pp. 797-801 ◽  
Author(s):  
Takayuki Ishida ◽  
Takuya Kanetomo ◽  
Masaru Yamasaki
Keyword(s):  
High Spin ◽  
Room Temperature ◽  
Spin Crossover ◽  
Spin Transition ◽  
Complex Salt ◽  
Magnetic Study ◽  
The Novel ◽  
Bond Lengths ◽  
External Stimuli ◽  
Spin Species

The spin-crossover phenomenon is a reversible low- and high-spin transition caused by external stimuli such as heat. In the novel iron(II) complex salt tetraphenylphosphonium tris(thiocyanato-κN)[1,1,1-tris(pyridin-2-yl)ethane-κ3N,N′,N′′]ferrate(II), (C24H20P)[Fe(NCS)3(C17H15N3)], the Fe—N bond lengths are in the range 2.027 (2)–2.089 (2) Å, indicating that the specimen consists of comparable molar fractions of the low- and high-spin species at 296 K. A magnetic study confirmed that spin-crossover takes place at around 290 K.

Iron(II) Mononuclear Materials Containing Functionalised Dipyridylamino-Substituted Triazine Ligands: Structure, Magnetism and Spin Crossover

2012 ◽  
Vol 65 (7) ◽  
pp. 874 ◽  
Author(s):  
Hayley S. Scott ◽  
Tamsyn M. Ross ◽  
Stuart R. Batten ◽  
Ian A. Gass ◽  
Boujemaa Moubaraki ◽  
...  
Keyword(s):  
Field Strength ◽  
Crystal Field ◽  
Spin Crossover ◽  
Spin Transition ◽  
Magnetic Behaviour ◽  
Crossover Effect ◽  
Thermally Induced ◽  
Crystal Field Strength ◽  
Nitrogen Donor ◽  
Packing Interactions

The spin crossover effect in iron(II) materials containing the di-2-pyridylamine functional group has been investigated for the new nitrile-functionalised ligand DTAC (2,2′,2″,2″′-((6-(di(pyridin-2-yl)amino)-1,3,5-triazine-2,4 diyl)bis(azanetriyl))tetra acetonitrile). This ligand has successfully been incorporated into a family of materials of the general formula trans-[Fe(DTAC)2(anion)2], wherein we have systematically varied the trans-nitrogen donor anion from NCS, NCSe, N(CN)2 (dca; dicyanamide) to NCBH3 – thus forming the four mononuclear materials trans-[Fe(DTAC)2(NCS)2]·6MeCN (1), trans-[Fe(DTAC)2(NCSe)2]·6MeCN (2), trans-[Fe(DTAC)2(N(CN)2)2] (3) and trans-[Fe(DTAC)2 (NCBH3)2]·3MeCN (4)). We find that the materials with a weaker crystal field strength anion remain high spin over all temperatures (1 and 2) whereas the materials containing stronger crystal field strength anions undergo a thermally induced spin crossover (3 and 4). Structural analysis revealed that the packing interactions in the solid state and the degree of solvation also play a large role in the observed magnetic behaviour. Indeed, aged or rapidly precipitated samples of 2 show a spin transition above room temperature.

Metal complexes of 1,10-Phenanthroline derivatives. VIII. Complexs of 1,10-Phenanthroline-2-carbaldehyde imines

1974 ◽  
Vol 27 (10) ◽  
pp. 2121 ◽  
Author(s):  
HA Goodwin ◽  
DW Mather
Keyword(s):  
High Spin ◽  
Room Temperature ◽  
Spin Transition ◽  
Significant Rise ◽  
High Field Strength ◽  
Aryl Group ◽  
Metal Atoms ◽  
Spin Pairing ◽  
Aryl Amines ◽  
Derivatives Of

Iron(11), cobalt(11) and nickel(11) complexes [ML2] [BF4]2 of a series of related tridentate imine derivatives of 1,l0-phenanthroline-2-carbaldehyde [N-(l,l0-phenanthrolin-2-ylmethylene)alkyl-(or aryl)amines in which the alkyl or aryl group is methyl, ethyl, propyl, isopropyl, butyl, s-butyl, t-butyl, phenyl or benzyl] are described. From the electronic spectra of the nickel complexes an order of field strengths is established which correlates reasonably well with the bulkiness of the imine moiety. All the ligands except that where R = But effect spin-pairing in iron(11) at room temperature. When R = But the iron(11) complex is essentially high-spin at room temperature but is predominantly low-spin at 83 K. The magnetism of this substance is typical for that of iron(11) systems in which a gradual spin transition, 5T2 ←→ lAl occurs. In the complexes where R = Bu Bu8, Ph, a significant rise in the magnetic moment above room temperature is observed, indicating the presence of some metal atoms in the 5T2 state. Certain of the ligands of high field strength (R = Me, Et, Pr, Pr1) yield cobalt(11) complexes whose magnetism is indicative of a gradual quartet-doublet transition. The remaining cobalt(11) complexes are high spin.

Evidence for high-spin-to-low-spin transition under pressure in Fe 72 Pt 28 Invar alloy

2000 ◽  
Vol 80 (2) ◽  
pp. 155-163 ◽  
Author(s):  
S. Odin, F. Baudelet, E. Dartyge, J. P
Keyword(s):  
High Spin ◽  
Spin Transition ◽  
Invar Alloy
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